The Astronomical Observatories of Jai Singh c10.34

c10.34

39. The Rām Yantra consists of two large circular buildings, complementary to each other, situated south of the Jai Prakāś. Their general structure is best seen in figures 39, 41, 47-49 and in the plates XIII and XVII. Each consists of a circular wall and a pillar at the centre. The height of the walls and pillar, from the graduated floor, is equal to the inside radius of the building measured from the circumference of the pillar to the wall, viz., 24 feet 6½ inches, and the diameter of the pillar is 5 feet 3½ inches. The walls and floor are graduated for reading horizontal (azimuth) and vertical (altitude) angles. To facilitate observation the floor is cut up into thirty sectors, with the spaces between of the same angular dimensions as the sectors, viz., six degrees. The graduated sectors are supported on pillars three feet high, so that the observer can ‘place his eye’ at any point on the scale. The graduated walls are, similarly, broken up by openings, at the sides of each which are notches for placing sighting bars. At Delhi there are no such bars in evidence but at Jaipur they are faced with brass and carefully graduated. At Jaipur the central